1. Field of the Invention
The present invention relates to a valve and, more particularly, to a diaphragm valve having a diaphragm which functions as a valve body.
2. Prior Art
Diaphragm valves have conventionally been known and one of these valves will be described in detail hereinafter in relation to the preferred embodiments of the present invention. However, this known conventional diaphragm valve has had the disadvantage that due to the structural relationship between the diaphragm and the plate portion of the retainer for pressing the diaphragm, when the diaphragm valve is operated in a low temperature atmosphere around -30.degree. C., the sealing section of the diaphragm sticks to the valve seat due to freezing while at the same time, when it is operated in a high temperature atmosphere, the like sticking phenomenon also takes place between the diaphragm and the valve seat due to heating of the diaphragm so that the pressure and flow rate characteristics of the valve changes greatly to thereby prevent the valve from performing an accurate valve opening operation.